1. Field of the Invention
This invention relates to the use of polyfunctional quaternary ammonium compounds which are substantially insoluble in aqueous detergent solutions and/or are immobilized on solids insoluble in such solutions, for the regeneration of soil-laden aqueous detergent solutions.
2. Discussion of the Related Art
The subject of prior International Patent Application PCT/EP/86/753 is the use of polyfunctional quaternary ammonium compounds (PQUATS) which are insoluble in aqueous-surfactant laundering and cleaning solutions even under the temperature loads of the laundering process, and/or are present in immobilized form such that they cannot be washed off from solids appropriately insoluble in these aqueous solutions, as particulate soil-collecting cleaning enhancers in aqueoussurfactant laundering and cleaning solutions, which following the laundering or cleaning of the material to be cleaned, can be removed manually and/or mechanically from the cleaning solution. In this prior application, the laundering power enhancement of the customary aqueous-alkaline textile laundry detergent solutions by the simultaneous use of such PQUAT soil collectors is especially described. At least a considerable fraction of the soil solubilized during textile laundering, especially the pigmented soil, is taken up by the PQUAT present in the solid phase, and thus is ultimately transferred from the originally soiled textile material to to be cleaned to the soil collector. An increase in the reflectance value of the laundered material can be established in the laundering result in this way under selected conditions.
The present teaching extends the novel application of such PQAUTS in that improvements are not only achieved in terms of the laundering result on the textile to be cleaned; in addition, new possibilities are pointed out for using surfactant laundering and cleaning solutions of the type mentioned more effectively and more economically. The teaching in accordance with the invention especially creates the possibility of reuse, possibly of repeated reuse, of the aqueous phase of soiled cleaning baths, in that by treating these baths with the insoluble or immobilized PQUATS mentioned in the earlier application cited above, the soil solubilized in the bath is at least partially precipitated on the undissolved PQUAT, and thus the contaminated cleaning bath is at least partly freed from its soil load. Part or all of the aqueous bath treated in this way can be taken for reuse for new cleaning operations. It is apparent that important advantagaes in several regards are achieved in this way. On one hand, the economy of such cleaning processes can be increased through the reuse of chemical fractions which were previously discharged into the waste water together with the removed soil, and on the other hand it is possible in this way to achieve effective reduction of environmental pollution in the sense of protecting bodies of water against discharged laundry chemicals. Even though a certain loss of chemicals is unavoidable, for example, the fraction of the surfactant that is lost when the textile material is rinsed, nevertheless the invention offers important advantages in the indicated way. Whereas previously the entire chemical load was introduced into the waste water system together with the soiled bath, according to the new process a considerable fraction is immobilized as the solid phase, and other dissolved fractions can be recycled in the aqueous bath.